Moisture stabilized asphalt coated fiberboard and method for making the same



Aug. 16, 1966 6 2 uw 6 6 2 3.. D R A O B R E IDW F A D S E E NM H Aw T M G Rum EM M MPM www ZDF mw .IH Gum. B E A M T D S N EA R U T s I O M 2 Sheets-Sheet 1 Filed NOV. 14, 1962 PEN TR H Morney United States Patent O corporation of Delaware Filed Nov. 14, 1962, Ser. No. 237,479 S Claims. (Cl. 117-62) The present invention is directed to an asphalt coated berboard, and more particularly to an asphalt coated berboard having a controlled amount of moisture therein.

Fiberboards made from organic fibers have found extensive use as insulating sheathing in the construction of buildings. They have been used for insulating sidewalls of buildings beneath exterior siding such as wood, brick, etc. In addition, they have been used for insulation as an integral part of roofing.

To further protect the sheathing against the absorption of excessive moisture, such berboards are conventionally coated with a thin asphalt coating. Consequently, in use, the iiberboards may be left out-of-doors without regard for rain or inclement weather conditions.

However, because of the asphalt coating, the stabilization of moisture within the iiberboard presents a difficult problem. It has been found that for optimum dimensional stability of the iiberboard, there should be about 6% to 8% by weight of water in the board when delivered from the factory to the job site. It the board does not contain this amount of moisture when installed, it will absorb this amount over the course of months or years and will expand, resulting in buckling of the berboard.

In manufacturing the iberboard from vegetable fibers, such as wood fibers or bagasse, the board is formed from an aqueous slurry on a Fourdrinier or cylinder papermaking machine and then dried in an oven.

After the iiberboard is dried, the moisture must be added. If the moisture in the form of water is added before the berboard receives its asphalt coating, then the asphalt fails to penetrate properly and gives an unsightly appearance to the berboard in the form of shiny spots on the surface. In addition, the fiberboards stick together when they are stacked in storage, and when removed, are rejected for torn surfaces.

If, on the other hand, the iiberboards are coated with asphalt before the moisture is added, the coating forms an almost impenetrable shield and prevents moisture from entering the board.

The problem, therefore, is to provide a liberboard having about 6 to 8% moisture therein by weight despite the fact that the board must have an asphalt coating. Certain surface active or wetting agents have been used so that moisture will enter the iiberboards after coating. However, in general, these surface active agents, while they get moisture into the boards, permit more moisture than can be tolerated.

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However, certain cationic acetic salts of fatty acid amines have been found which aid in the absorption of moisture into the board in the correct amount for dimensional stability. In addition, surprisingly, after the moisture has been added, these acetic acid salts themselves also become water repellent after drying and prevent further moisture from penetrating the board. Thus, these salts have the surprising quality of enabling penetration of moisture to the proper amount and then preventing further absorption.

It is an object of the present invention to provide a novel asphalt coated berboard with dimensional stability through the addition of a controlled amount of moisture.

It is another object of the present invention to provide a novel asphalt coated iiberboard which, while containing a controlled amount of moisture for dimensional stability, does not readily absorb additional moisture, even when left out-ofadoors in the rain.

It is yetanother object of the present invention to provide a novel asphalt coated berboard which can be stacked in layers without sticking together.

These and other objects and advantages of the present invention will become apparent when taken in consideration with the accompanying drawings, in which:

FIGURES l and 2 are graphical representations of data useful in understanding the invention.

As has been explained, it is necessary to insure a moisture condition of about 6% to 8% by weight in the asphalt coated fiberboard. In order to add suiiicient moisture after the asphalt coating has been applied, an acetic acid salt of a fatty acid amine is added in an aqueous solution with the proper concentration of such salt to produce the moisturized condition.

The molecular formula for the acetic acid salt of a fatty amine is:

[RNH3]+[CH3COO]* where R represents an alkyl group derived from the fatty acids ranging in carbon chain length from 8 to 18 carbon atoms.

Thus, the fatty acid series from caprylic acid to stearic acid form the basis of the fatty acid amine. The acetic acid salt formed from the combination of the fatty acid amine radical and the acetic acid radical is formed from the fatty acid series having from 8 to 18 carbon atoms in the chain.

Acetic acid salts of fatty amines suitable for the purposes herein defined are sold by the Armour Industrial Chemical Company, a division of Armour & Company of Chicago, Illinois, under the registered trademark Armac The following table sets forth the composition of the fatty acid chain for various of the compounds.

In the following table, the numbers in the parentheses represent the number of carbon atoms in the fatty acid component of the acetic acid salt. The numbers opposite the compounds represent the percents of the fatty acid components shown above the numbers.

Table I Octa- Octa- Iltxyl Octyl Decyl Dodecyl Tetra- Hexaecyl decenyl (u) (8) (10) (12) decyl decyl Saturated Mono- Armac 8D Of the compounds set forth in the chart, Armacs 8D, 12D, HT, C and T have been tested in the laboratory and found to produce the surprising :results of moisture penetration and subsequent waterproofing of the present invention.

Not only must the proper acetic acid salt of a fatty acid amine be selected, but its concentration in an aqueous solution is important in the instant application. It is necessary that the moisture penetration be rapid so that an undue slowing of the manufacturing process be avoided. At speeds of 200 feet per minute for the application of the aqueous solution to the berboard, quick penetration of the moisture becomes essential. Reference may now be had to FIGURE 1, in which the time of penetration in 'minutes of the aqueous solution of the compound is plotted graphically against the concentration of the solution. The concentration is given in terms of percent by weight of the acetic acid salt in water. Curves A, B, C, D and E correspond directly to the compounds Armac C, Armac 12D, Armac T, Armac HT, and Armac 8D. may be seen from FIGURE 1 that, in general, as the concentration of the additive solution increases from about .25% to 1.0%, the penetration time decreases from more than 2 minutes to a range between .l2 to .23 minute. For test conditions, about 1 milliliter of solution was applied to an asphalt coated fiberboard having a surface area of 3.5 square cm. The board temperature was about 220 F., which is approximately its temperature at the time the solution would be applied in production. The optimum concentration falls between 1% and 3%. Beyond 3% the time of penetration begins to increase. The major eX- ception -to this is Armac 8D (line E) which shows an opti-mum penetration time for a concentration of 8%. However, for economic reasons, the cost of Armac 8D at the concentration needed prohibits its use.

Consequently, the optimum concentration of the additive solution lies between 1% and 3%. Concentration between .3% and 8% may be tolerated.

In order to provide 6% to 8% moisture in the fiberboard, an amount of 6 to 8 pounds of the aqueous solution of the acetic acid salt should be added to 100 pounds of fiberboard. This can be done by spraying this amount of solution on the board as it emerges from the asphalt coater. The thickness and density of the iiberboard as well as the speed at which the board is conveyed from the drier are factors to deter-mine the actual amount of water to be sprayed in any given time. However, these calculations can be easily made by those skilled in the art.

As an example, for a board 10 feet wide and 1 inch thick, having a density of l2 pounds per cubic foot, being conveyed at 200 lineal feet per minute, 160 pounds of aqueous solution should be evenly sprayed over the surface of the board per minute.

To illustrate the stabilizing effect which the acetic acid salt of a fatty amine has on the moisture in the board, fberboards after manufacture and drying were immersed for 24 hours in water. Thus, a severe moisture condition was simulated. The boards, however, for concentrations within the optimum range found in FIGURE 1, showed excellent inhibition to moisture pick-up. Reference to FIGURE 2, which is a graph of percent weight inc-rease in moisture against concentration in percent by weight of additive solution, illustrates the usefulness of the additive. For concentrations between .25% and 1%, the increase in moisture pick-up varies from about to 22% compared with a board with 8% moisture originally added. Beyond 1% concentration for the shorter carbon chain radicals, the moisture pick-up increases more rapidly than the moisture pick-up for the longer chain radicals.

From a comparison of FIGURES 1 and 2, the conclusion is reached that the optimum conditions of moisture stabilization are achieved with a concentration of higher fatty acid radicals (16-18 carbon atoms) in a concentration range of between 0.5% and 3% by weight. For comparison, a control board which had 8 moisture by weight,

but no acetic acid salt of a fatty acid amine added, had a moisture increase to about 19% by weight. This latter amount of moisture increase is slightly higher than that of a board with an added amount of solution with a higher fatty acid chain up to a concentration of 2% and almost to 3%.

The results of this test procedure are more severe than is conventionally found in practice. In general, the board is not immersed in water for a period of 24 hours on the job. But it will stabilize at about 6 to 8% moisture content.

In addition, the fiberboards incorporating acetic acid salt of the fatty acid amine cool more rapidly than do boards not so treated. The board will cool in about two or three days when stacked. Other boards not so treated with an aqueous solution may require weeks to cool.

The present invention, therefore, is directed to an asphalt coated iberboard incorporating an aqueous solution of an acetic acid salt of a fatty acid amine to achieve dimensional stability by the controlled stabilization of moisture therein. The particular concentration of the solution is of importance, as well as the length of the fatty acid chain.

While various embodiments of the present invention have been described, some changes and modifications will occur to those skilled in the art, and it is intended to cover such changes and modifications in the appended claims.

I claim:

1. An asphalt coated berboard comprising:

a mat of interfelted organic bers,

a coating of asphalt covering said mat and an acetic acid salt of a fatty amine integrally dispersed in said mat, said acetic acid salt being in aqueous solution having a concentration of about 1% to 3% by weight of said salt and in an amount to leave about 6% to 8% by weight of moisture in the board.

2. An asphalt coated berboard, as in claim 1, in which said acetic acid salt of a fatty amine contains an alkyl group derived from the fatty acids ranging in carbon chain length from 8 to 18 carbon atoms.

3. The method of incorporating about 6% to 8% moisture in an asphalt coated fiberboard comprising the step of:

applying to one surface of said board while at a ternperature of about 220 F. an acetic acid salt of a fatty 4amine in an aqueous solution having a concentration of about 1% to 3% by weight of said salt and in an amount to leave about 6% to 8% by Weight of moisture in the board.

4. The method of incorporating about 6% to 8% moisture in an asphalt coated fiberboard comprising the step of:

applying to one surface of said board while at a temperature of about 220 F. an acetic acid salt of a fatty amine in an aqueous solution having a concentration of about 0.25% to 8% by weight of said salt and in an amount to leave about 6% to 8% by weight of moisture in the board.

5. An asphalt coated berboard comprising:

a mat of interfelted organic bers,

a coating of asphalt covering said mat and an acetic acid salt of a fatty amine integrally dispersed in said mat, said acetic acid salt being in aqueous solution having a concentration of about 0.25% to 8% by weight of said salt and in an amount to leave about 6% to 8% by weight of moisture in the board.

References Cited by the Examiner UNITED STATES PATENTS WILLIAM D. MARTIN, Primary Examiner.

R. HUSACK, Assistant Examiner. 

4. THE METHOD OF INCORPORATING ABOUT 6% TO 8% MOISTURE IN AN ASPHALT COATED FIBERBOARD COMPRISING THE STEPS OF: APPLYING TO ONE SURFACE OF SAID BOARD WHILE AT A TEMPERATURE OF ABOUT 220*F. AN ACETIC ACID SALT OF A FATTY AMINE IN AN AQUEOUS SOLUTION HAVING A CONCENTRATION OF ABOUT 0.25% TO 8% BY WEIGHT OF SAID SALT AND IN AN AMOUNT TO LFEAVE ABOUT 6% TO 8% BY WEIGHT OFF MOISTURE IN THE BOARD. 